Forceful flick, using the other hand (4)
I believe the answer is:
firm
'forceful' is the definition.
(similar in meaning)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for firm that I've seen before include "Unflinching" , "Solid; secure" , "Steadfast" , "Company - stable" , "Stable; business" .)